Large companies do not generally innovate. Their internal inertia prevents them from successfully creating new things. Also the larger a company gets, the more layers of brainless MBA parasites latch on to suck them dry.

Large companies rely on purchasing innovation by buying up a never ending stream of smaller companies. They then take the ideas/products and launch them to a wider market.

Steam has remained small by rejecting massive buyout offers. This has allowed them to remain innovative.